The present invention is an improved vacuum disc-type precision seed planter. It is particularly well adapted for planting double rows of seed at high speeds with a high degree of accuracy in seed placement. Multiple units may be assembled side-by-side on a tool bar so that all the rows in a wider bed may be planted simultaneously.
Seed planters, sometimes called seed drills, have been known for many years. They are called upon to handle a wide variety of different sizes, shapes and weights of seeds. These may range from very minute seeds, such as carrot or celery, to large seeds, of which corn and the various types of beans are exemplary. These seeds must be planted with different spacings between plants within a given row and between rows. Spacing is heavily dependent on the size the plants obtain at harvest time. For many crops, the optimum planting time is relatively short. In some cases, many hundreds of acres may need to be planted within a total time not exceeding a week or ten days. Unfavorable weather may still further limit the available planting time. For this reason, agricultural seed planters must be rugged and reliable since major breakdowns could prove disasterous to the farmer who might not then be able to get his crop sown in the prescribed time period.
The importance of planting a given crop at optimum spacing between plants and between rows has been recognized for some time. If seeds are planted irregularly, or too close together, the ultimate crop yield may be reduced. If planted too far apart, the farmer is not achieving optimum use of his valuable land. Considerable precision in ultimate seed placement is becoming more and more demanded in sowing units. The advent of mechanical harvesting machines for greater varieties of crops places further demands on accuracy of seed placement.
A considerable number of excellent seed sowers are available on the market today. An individual sowing unit normally comprises a means of opening a furrow, means for singulating seeds from a seed supply, means for transferring the singulated seed into the furrow at some predetermined spacing, and means for closing the furrow. The singulation process is one of the key elements in any successful planter. A number of systems have been developed to accomplish this purpose. Among them are ones which have a plate or drum containing a multiplicity of cavities designed to accommodate only a single seed of the crop being sown. Others are arranged like spokes on a wheel and have small cups at the end of each spoke which will accommodate only a single seed. These devices normally rotate through a supply of seed which is maintained constant by the flow from a hopper or other source.
Vacuum-type seeders are more pertinent to the present invention. These may have either a relatively flat disc or an elongated drum whose interiors are in communication with a fan or other device to reduce the air pressure within the unit. In the case of drums, they are usually provided with multiple rows of circumferential holes which serve to pick up seeds from a seed source due to the reduced pressure within the drum. Disc-type sowers work in similar fashion except that they normally have a circular array of small holes near the periphery and act to pick up seed for only one crop row at a time. Both types have some means to release the seed at the desired point, whereupon it either falls directly into a furrow or into a tube or chute which conveys it to a furrow. Various recent examples of drum type seeders can be seen in U.S. Pat. Nos. to Boots, 4,145,980; Luttrell, 4,210,260; Feltrop, 4,265,368; Hassan et al., 4,306,509; and West German DE No. 30 03 919 to Becker. Examples of disc-type seeders employing an internal vacuum to hold seeds to the face of the disc are seen in Soviet Union Pat. Nos. 745,410; 738,536; 762,773 and in U.S. Pat. Nos. to Gugenhan, 3,990,606; Harrer, 4,241,849; and Tye 4,285,444. While this list is exemplary rather than exhaustive, it does include all of those devices which the present inventor believes to be most closely related to the present invention. The patents to Tye and Gugenhan are of the greatest pertinence and will be discussed in more detail.
Gugenhan U.S. Pat. No. 3,990,606 is exemplary of a single row vacuum disc-type seeder which has experienced considerable commercial success. A single seeder unit has at its heart a thin, rotatable drum or disc unit the interior of which is connected to a vacuum source. The face of the drum has a single circle of suction holes near its periphery. A hinged seed chamber partially encloses the face of the drum and acts as a reservoir of seeds. These are held to the holes by the internal vacuum as the drum rotates through the seeds. There is a tendency in a device of this type for more than one seed to become attached to each individual hole. A number of different types of seed singulation mechanisms have been developed for vacuum disc-type seeders. These usually comprise a stationary bar or some similar means which brushes the seeds as they rotate past. These often have saw toothed, or serrated edges so that the seeds are bumped two or three times. This gentle agitation is usually sufficient to dislodge all but the single seed which is most tightly held against the hole. As the seed disc continues to rotate, an internal device blocks the hole at a given point so that the vacuum can no longer effectively hold the seed which drops off into the furrow or planting tube. Some sowers, such as the example to Gugenhan, also have an external bar which dislodges the seed simultaneously with the action of the vacuum breaker. One deficiency of the Gugenhan type device is the fact that any seed within the hopper will be spilled if it is ever necessary to open the hinged plate comprising this seed pick up reservoir. A field situation when this could be required is when a number of holes in the pickup disc have been become plugged by dirt or other debris. Because there must be access from the side to open the hinged seed reservoir, sowers of this type are not suitable for planting double rows.
While most crop plants are sown in single rows, sometimes higher densities can be achieved if each row actually is a double row in which the two individual rows are separated by only a few centimeters. Plants in these rows may sometimes be staggered to give more effective growing space. Double row seeding is readily accomplished with drum type sowers; e.g., Hassan et al., U.S. Pat. No. 4,306,509 or Luttrell U.S. Pat. No. 4,210,260. However, these sowers do not generally operate at a level of speed and reliability which is desirable for high speed precision planting. To the present inventor's knowledge, there is no disc-type seeder commercially available which will conveniently sow a double row. Presumably, the sower shown in U.S. Pat. No. 4,285,444 to Tye could be modified for double row sowing. The Tye device uses a pair of opposed sower discs a short distance apart. These pick up seed from a common hopper and seed trough and discharge into a single planting tube. However, the Tye mechanism is of relatively complex construction and cannot be conveniently disassembled in the field if the apertures should become plugged or some other problem arises. If this were the case, it would be virtually necessary to return the offending seeder unit to the shop with the resulting significant loss of planting time, or to have a replacement unit in the field which could be substituted. Even the installation of a replacement unit requires some tools and a certain amount of mechanical skill on the part of the tractor driver. There is no convenient way to remove any seeds left in the unit after sowing or before disassembly.
The present invention overcomes many of the problems associated with disc-type vacuum seeder heads. It can sow double rows, if desired, at high speed and with a high degree of precision. Further, the seeder can be rapidly and easily disassembled in the field for repair or cleaning without the need for any tools and without loss of seed.